Integrated circuit and other semiconductor devices are widely used electronic devices that find practically unlimited application in today's world. Designers of these semiconductor devices are continually challenged to increase integration levels by using a multitude of scaled down transistors and other scaled down features to increase device performance and device density. The active devices that are being formed in closer and closer proximity must be electrically isolated from one another.
Shallow trench isolation (STI) is a technique used to reduce isolation width while maintaining the necessary electrical isolation between adjacent active devices. Shallow trench isolation (STI) is being used with integrated circuits in the 0.25 micrometers and below range to achieve necessary performance and design rules. Conventional STI devices employ silicon oxide to fill the shallow trenches and isolate devices.
The oxides for the STI fill are typically deposited using techniques which provide for oxide deposition on the trench bottom, sidewalls, and over the semiconductor substrate in non-trench areas. The nature of the deposition results in a weak seam at the center of the trenches where the oxide from the two sides of the trenches meet. Silicon oxides become attacked in HF (hydrogen fluoride) and other wet chemical solutions which are heavily used in semiconductor processing for operations such as oxide stripping, wet oxide etching, pre-cleans prior to oxide formation processes and pre-cleans prior to other deposition and feature formation processes. Because HF wet processing operations and other wet oxide etching processing operations are so commonly used in semiconductor manufacturing, the oxide STI structures with oxide surfaces are very prone to attack especially when overlying contact layers are not perfectly aligned. The seam at the middle of the STI structure may become attacked, divots may be created at the interface between the STI oxide and the trench sidewall and the entire top surface of the oxide STI structure may become receded progressively with each of the several wet HF processing operations that are subsequently carried out.
It would therefore be advantageous to provide an STI structure that is formed of a durable material that is resistant to attack during subsequent processing operations necessary to manufacture semiconductor devices.